Transmission bands are used to act as a brake or clutch to stop a rotating drum member of a transmission. The interior circumference of a transmission band is usually lined with a friction material to assist in achieving the smooth cessation of drum rotation. The ends of a transmission band generally have brackets or lugs known as apply and reaction members which are used to anchor the band member and engage apply pin members located within the transmission, The reaction member is usually anchored and the apply pin engages the apply member to push the apply member toward the reaction member, thereby decreasing the circumference of the band and causing the band to frictionally engage the rotating members or drums within the transmission to brake those members to a stop.
Commonly, prior art transmission bands have been designed to provide endurance under the stressful, repetitive conditions found in the operation of a transmission. Most often these heavy, thick, bands have a thickness or gauge of around 0.080 inches (0.20 cm), allowing the band to enjoy a long life and yet provide some flexibility during application of the band to the rotating transmission drums. However, with the advent of higher fuel costs and automotive manufacturing demands for fuel efficiency, recent research has centered around producing transmission bands of lighter weight materials and thinner cross sections. Development of these lighter weight bands having thinner cross section designs has been plagued by increased problems in the overall quality of the transmission bands and their ability to perform the required repetitive and stressful functions.
A typical single wrap transmission band is formed as a strip of sheet metal having a friction lining adhered about the interior circumference with separate apply and reaction members attached to the ends of the strap members. The apply and reaction members are commonly manufactured as formed brackets which are secured to the strap by an appropriate form of attachment such as a tab lance, extrusion, spot weld, or structural adhesive. The application of these heavy forged apply and reaction members to the lighter, thinner straps is, however, counter-productive to meeting the demands of the automotive manufacturers for lighter weight components. The prior art forged apply and reaction brackets not only have a relatively thick cross section and substantial added weight, they interfere with the potential for enhanced operation characteristics of the transmission band. Transmission bands manufactured from a thinner gauge sheet metal have enhanced operational characteristics when compared to the prior art thicker gauge bands especially in the ability of the band to conform to the rotating drums of the transmission and wear evenly about the band. Bands manufactured with the thick forged apply and reaction brackets, however, do not have the desired flexibility toward the ends of the band where the apply and reaction members are attached and the band, therefore, does not engage, with uniformity, around the rotating transmission pieces. Thus, there is an enhanced possibility of uneven wear of the transmission bands.
Problems have also been encountered with known transmission bands that have been designed to incorporate lighter-weight apply and reaction brackets. A noticeably reduced ability in the load carrying capability of the transmission band commonly results from a premature failure of the band due to stress and fatigue of the lighter-weight apply and reaction members.
Therefore, it is an object of this invention to provide a transmission band which engages the rotating transmission members with greater conformity than current bands.
A further object of this invention is to provide a lightweight, one-piece transmission band having the apply and reaction member integrally formed in the base material.
Yet another object of this invention is to provide a lightweight, one-piece transmission band having load carrying capabilities at least as good if not better that those of the heavier common prior art bands.